设计模式-状态模式

状态模式允许对象在内部状态改变时改变它的行为，对象看起来好像修改了它的类。
一般来讲，当状态转换时固定的时候，就适合放在Context 中；然而，当转换时更动态的时候，就适合放在状态类中。

public interface State {
	abstract void insertQuarter();
	abstract void ejectQuarter();
	abstract void turnCrank();
	abstract void dispense();
}

public class HasQuarterState implements State {
	Random randomWinner = new Random(System.currentTimeMillis());
	GumballMachine gumballMachine;
	
	public HasQuarterState(GumballMachine gumballMachine) {
		this.gumballMachine = gumballMachine;
	}
	@Override
	public void insertQuarter() {
		System.out.println("You can't insert another quarter.");
	}

	@Override
	public void ejectQuarter() {
		System.out.println("Quarter returned.");
		gumballMachine.setState(gumballMachine.getNoQuarterState());
	}

	@Override
	public void turnCrank() {
		System.out.println("You turned...");
		int winner = randomWinner.nextInt(10);
		System.out.println("-----------------winner :" + winner);
		if ((winner == 0) && gumballMachine.getCount() > 1) {
			gumballMachine.setState(gumballMachine.getWinnerState());
		} else {
			gumballMachine.setState(gumballMachine.getSoldState());
		}
	}

	@Override
	public void dispense() {
		System.out.println("No gumball dispensed.");
	}

}

public class NoQuarterState implements State {
	
	GumballMachine gumballMachine;
	
	public NoQuarterState(GumballMachine gumballMachine) {
		this.gumballMachine = gumballMachine;
	}
	
	@Override
	public void insertQuarter() {
		System.out.println("You inserted a quarter.");
		gumballMachine.setState(gumballMachine.getHasQuarterState());
	}

	@Override
	public void ejectQuarter() {
		System.out.println("You haven't inserted a quarter.");
	}

	@Override
	public void turnCrank() {
		System.out.println("You turned, but there's no quarter.");
	}

	@Override
	public void dispense() {
		System.out.println("You need to pay first.");
	}

}

public class SoldOutState implements State {
	GumballMachine gumballMachine;
	
	public SoldOutState(GumballMachine gumballMachine) {
		this.gumballMachine = gumballMachine;
	}
	@Override
	public void insertQuarter() {
		System.out.println("You can't insert a quarter, the machine is sold out.");
	}

	@Override
	public void ejectQuarter() {
		System.out.println("You can't eject, you haven't inserted a quarter yet.");
	}

	@Override
	public void turnCrank() {
		System.out.println("You turned, but there are no gumballs.");
	}

	@Override
	public void dispense() {
		System.out.println("No gumball dispensed.");
	}
}

public class SoldState implements State {
	GumballMachine gumballMachine;
	
	public SoldState(GumballMachine gumballMachine) {
		this.gumballMachine = gumballMachine;
	}
	@Override
	public void insertQuarter() {
		System.out.println("Please wait, we're already giving you a gumball.");
	}

	@Override
	public void ejectQuarter() {
		System.out.println("Sorry, you already turned the crank.");
	}

	@Override
	public void turnCrank() {
		System.out.println("Turning twice doesn't get you another gumball.");
	}

	@Override
	public void dispense() {
		gumballMachine.releaseBall();
		if (gumballMachine.getCount() > 0) {
			gumballMachine.setState(gumballMachine.getNoQuarterState());
		} else {
			System.out.println("Oops, out of gumballs.");
			gumballMachine.setState(gumballMachine.getSoldOutState());
		}
	}


}

public class WinnerState implements State {

	private GumballMachine gumballMachine;
	public WinnerState(GumballMachine gumballMachine) {
		this.gumballMachine = gumballMachine;
	}
	
	@Override
	public void insertQuarter() {
		System.out.println("Please wait, we're already giving you a gumball.");
	}

	@Override
	public void ejectQuarter() {
		System.out.println("Sorry, you already turned the crank.");
	}

	@Override
	public void turnCrank() {
		System.out.println("Turning twice doesn't get you another gumball.");
	}

	@Override
	public void dispense() {
		System.out.println("You're a winnner! You get two gumballs for your quarter. ");
		gumballMachine.releaseBall();
		if (gumballMachine.getCount() == 0) {
			gumballMachine.setState(gumballMachine.getSoldOutState());
		} else {
			gumballMachine.releaseBall();
			if (gumballMachine.getCount() > 0) {
				gumballMachine.setState(gumballMachine.getHasQuarterState());
			} else {
				System.out.println("Opps, out of gumballs.");
				gumballMachine.setState(gumballMachine.getSoldOutState());
			}
		}
	}

}

public class GumballMachine {

	State soldOutState;
	State noQuarterState;
	State hasQuarterState;
	State soldState;
	State winnerState;
	
	State state = soldOutState;
	int count = 0;
	
	public GumballMachine(int numberGumballs) {
		soldOutState = new SoldOutState(this);
		noQuarterState = new NoQuarterState(this);
		hasQuarterState = new HasQuarterState(this);
		soldState = new SoldState(this);
		winnerState = new WinnerState(this);
		
		this.count = numberGumballs;
		if (numberGumballs > 0) {
			state = noQuarterState;
		}
	}
	
	public void insertQuarter() {
		state.insertQuarter();
	}
	
	public void ejectQuarter() {
		state.ejectQuarter();
	}
	
	public void turnCrank() {
		state.turnCrank();
		state.dispense();
	}
	
	public void releaseBall() {
		System.out.println("A gumball comes rolling out the slot....");
		if (count != 0) {
			count = count - 1;
		}
	}

	public void refill(int count) {
		this.count = count;
		state = noQuarterState;
	}
	
	public State getSoldOutState() {
		return soldOutState;
	}

	public void setSoldOutState(State soldOutState) {
		this.soldOutState = soldOutState;
	}

	public State getNoQuarterState() {
		return noQuarterState;
	}

	public void setNoQuarterState(State noQuarterState) {
		this.noQuarterState = noQuarterState;
	}

	public State getHasQuarterState() {
		return hasQuarterState;
	}

	public void setHasQuarterState(State hasQuarterState) {
		this.hasQuarterState = hasQuarterState;
	}

	public State getSoldState() {
		return soldState;
	}

	public void setSoldState(State soldState) {
		this.soldState = soldState;
	}

	public State getState() {
		return state;
	}

	public void setState(State state) {
		this.state = state;
	}

	public int getCount() {
		return count;
	}

	public void setCount(int count) {
		this.count = count;
	}

	public State getWinnerState() {
		return winnerState;
	}

	public void setWinnerState(State winnerState) {
		this.winnerState = winnerState;
	}

	@Override
	public String toString() {
		return "GumballMachine [state=" + state.getClass().getName() + ", count=" + count + "]";
	}
	
	
}

public class GumballMachineTestDrive {
	public static void main(String[] args) {
		GumballMachine gumballMachine = new GumballMachine(5);
		System.out.println(gumballMachine);
		
		gumballMachine.insertQuarter();
		gumballMachine.turnCrank();

		System.out.println(gumballMachine);
		gumballMachine.insertQuarter();
		gumballMachine.turnCrank();
		gumballMachine.insertQuarter();
		gumballMachine.turnCrank();
		
		System.out.println(gumballMachine);
	}
}